Positioning device for pressure regulator

ABSTRACT

A control assembly for converting a “fail-close” regulator to a “fail-open” regulator, or vice versa, without having to modify or reconfigure a casing of the regulator includes a control member, a central rod, and a spring disposed between first and second spring seats. A regulator including the control assembly includes a valve body and an actuator casing, the valve body defining a fluid flow-path. The control member is slidably disposed within the actuator casing and adapted for displacement relative to the valve body for controlling the flow of fluid through the flow-path. The spring and spring seats are disposed about the central rod, such that the spring biases the control member into a predetermined position relative to the regulator casing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 11/854,261,filed Sep. 12, 2007, and which claims the benefit of priority of U.S.Provisional Patent Application Ser. No. 60/827,588, filed Sep. 29, 2006,the entire contents of which are expressly incorporated herein byreference.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to a fluid control device and,more particularly, to a positioning device for a fluid control device.

BACKGROUND

Fluid control devices include various categories of equipment includingcontrol valves and regulators. Such control devices are adapted to becoupled within a fluid process control system such as chemical treatmentsystems, natural gas delivery systems, etc., for controlling the flow ofa fluid therethrough. Each control device defines a fluid flow-path andincludes a control member for adjusting a dimension of the flow-path.For example, FIG. 1 depicts a known regulator assembly 10 including avalve body 12 and an actuator 14. The valve body 12 defines a flow-path16 and includes a throat 18. In FIG. 1, the regulator assembly 10 isconfigured in a flow-up configuration. The actuator 14 includes an upperactuator casing 20, a lower actuator casing 22, a diaphragm subassembly30 including a diaphragm 32, and a control member 24.

The control member 24 is disposed within the upper and lower actuatorcasings 20, 22 and is adapted for bi-directional displacement inresponse to changes in pressure across the diaphragm subassembly 30. Soconfigured, the control member 24 controls the flow of fluid through thethroat 18. Additionally, as is depicted, the regulator assembly 10includes a seat ring 26 disposed in the throat 18 of the valve body 12.When the outlet pressure of the valve body 12 is high, a sealing surface28 of the control member 24 may sealingly engage the seat ring 26 andclose the throat 18. Similarly, absent any pressure in the actuator 14or upon the failure of the diaphragm 32, a coil spring 34 disposedwithin an annular cavity portion 36 of the upper actuator casing 20biases the control member 24 into the closed position. Such a regulatoris commonly known as a “fail close” regulator.

“Fail close” regulators are configured such that upon the occurrence ofa leak in the system, which removes pressure from the actuator 14, or afailure of the diaphragm 32 such as a tear, the control member 24automatically closes the flow of fluid through the regulator 10. Undersuch a circumstance, fluid delivery to the desired end-location ceasesuntil the regulator is repaired.

To avoid the necessity of terminating fluid delivery under failureconditions, some fluid process or delivery systems incorporate a “failopen” regulator. “Fail open” regulators operate similar to “fail closed”regulators; however, upon failure of the diaphragm, a spring biases thecontrol member open, rather than closed. Thus, even when the diaphragmor other control component fails, fluid continues to flow through theregulator uninterrupted and uncontrolled. Such configurations thereforeoften include a monitor regulator, which controls the fluid flow whenthe “fail open” regulator fails.

Conventional regulators are generally configured as either “fail open”or “fail close.” To reconfigure a “fail open” regulator to operate as a“fail close” regulator, or vice versa, the control assembly and theregulator casing often must be reconfigured or replaced with a differentcontrol assembly and regulator casing. Such reconfiguration and/orreplacement of the regulator casing can be costly and time-consuming.

SUMMARY OF THE DISCLOSURE

One embodiment of the present disclosure provides a positioning deviceassembly for regulating the flow of a fluid through a fluid flow-path ofa regulator. The positioning device assembly comprises a control member,a central rod, a first spring seat, a second spring seat, and a spring.The central rod is adapted to be disposed through a casing of theregulator. The first spring seat defines an opening receiving thecentral rod and is fixed relative to the central rod. The second springseat defines an opening receiving the central rod and is fixed relativeto one of the regulator casing and the control member. The spring isdisposed between the first and second spring seats and biases thecontrol member into a predetermined position relative to the regulatorcasing.

Another embodiment of the present disclosure comprises a regulatorcomprising a valve body defining a flow-path, an actuator casing coupledto the valve body, a control member, a central rod, first and secondspring seats, and a spring. The control member is disposed within theactuator casing and adapted for displacement relative to the valve bodyfor regulating a flow of the fluid through the flow-path. The centralrod is disposed through the actuator casing. The first spring seat isfixed relative to the central rod, and the second spring seat is fixedrelative to one of the actuator casing and the control member. Thespring is disposed between the first spring seat and the second springseat and biases the control member into a predetermined position withinthe casing of the regulator.

Yet another embodiment of the present disclosure provides regulatorcomprising a valve body, an actuator casing, a control member, and apositioning device assembly. The valve body defines a flow-path for afluid, and the actuator casing is coupled to the valve body. The controlmember is disposed within the actuator casing and adapted fordisplacement relative to the valve body for regulating a flow of thefluid through the flow-path. The positioning device assembly comprises acentral rod and a spring disposed about the central rod. At least aportion of the central rod is disposed within the control member, andthe spring biases the control member into a predetermined positionrelative to the valve body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional side view of one conventional “fail close”regulator;

FIG. 2 is a cross-sectional side view of one embodiment of a “fail open”regulator constructed in accordance with the principles of the presentdisclosure;

FIG. 3 is a cross-sectional side view of an alternative embodiment of acontrol assembly for the “fail open” regulator constructed according toFIG. 2; and

FIG. 4 is a cross-sectional side view of a second embodiment of a “failopen” regulator constructed in accordance with the principles of thepresent disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring to FIG. 2, a first embodiment of a control device constructedin accordance with the principles of the present disclosure includes apressure regulator 100. The pressure regulator 100 generally includes avalve body 102, a seat ring 104, and an actuator 106. The valve body 102defines a flow-path 108 extending between an inlet 110 and an outlet112, as well as into the actuator 106, as will be discussed. Theactuator 106 includes a control assembly 114 that is moveable between anopen position, as is shown in FIG. 2, and a closed position (not shown),wherein the control assembly 114 engages the seat ring 104. Movement ofthe control assembly 114 occurs in response to fluctuations in thepressure of the fluid at the inlet 110 and outlet 112. Accordingly, theposition of the control assembly 114 relative to the seat ring 104affects a flow capacity of the pressure regulator 100.

The valve body 102 further defines a throat 116 between the inlet 110and the outlet 112. The throat 116 includes a stepped portion 118accommodating and supporting the seat ring 104. In one form, an o-ringmay be disposed between the seat ring 104 and the stepped portion 118 ofthe throat 116 to provide a fluid-tight seal therebetween.

The actuator 106, as stated above, includes the control assembly 114 andadditionally, an upper actuator casing 122, a lower actuator casing 124,and a plurality of pins 126. The upper and lower actuator casings 122,124 are secured together by at least one threaded fastener 119 andcorresponding nut 121. The upper actuator casing 122 defines a centralopening 123, a first control inlet 125 (depicted in phantom), and atravel chamber 127. The travel chamber 127 contains a travel indicator131, which indicates the position of the control assembly 114 within theactuator 106. The lower actuator casing 124 defines a second controlinlet 129.

In cooperation, the upper and lower actuator casings 122, 124 define acavity 135 including a hollow neck 128. The hollow neck 128 is disposedwithin an actuator opening 115 in the valve body 102. As identified inFIG. 2, the plurality of pins 126 have first ends 126 a fixed to thehollow neck 128 and second ends 126 b located distally to the hollowneck 128. In the form illustrated, the first ends 126 a are threadedinto bores formed in the hollow neck 128. The second ends 126 b engagethe seat ring 104. Accordingly, the pins 126 and the stepped portion 118of the throat 116 sandwich and axially locate and secure the seat ring104 in the valve body 102. While the regulator 100 has been described asincluding a plurality of pins 126 locating the seat ring 104 relative tothe valve body 102, an alternate form of the regulator 100 may include acage disposed in the throat 116 to locate the seat ring 104. In anotherform, the seat ring 104 may be threaded, adhered, or otherwise fixed tothe valve body 102.

Still referring to FIG. 2, the control assembly 114 includes a controlmember such as a hollow sleeve 130, a mounting subassembly 132, adiaphragm subassembly 133, and a positioning device assembly 138. Thesleeve 130 is generally tubular defining a generally cylindrical innersurface 143 and a generally cylindrical outer surface 147. The innersurface 143 defines a central bore through the sleeve 130. Additionally,the sleeve 130 includes an upper end 130 a and a lower end 130 b. Theupper end 130 a is disposed within the cavity 135 and the lower end 130b is disposed within the hollow neck 128 of the lower actuator casing124. The upper end 130 a of the sleeve 130 is open and includes acircumferential flange 140 formed on the outer surface 147.Additionally, the upper portion 130 a of the sleeve 130 includes athreaded portion 141 on the inner surface 143. The lower end 130 b ofthe sleeve 130 is open and accommodates the mounting subassembly 132.

The mounting subassembly 132 includes a mounting member 142, a diskretainer 144, a disk holder 146, and a sealing disk 148. In thedisclosed form, the mounting member 142 includes a generally cylindricalbody threaded into the open lower end 130 b of the sleeve 130 anddefining a through-bore 150. The through-bore 150 is generally axiallyaligned with the sleeve 130. The disk retainer 144 includes a generallycylindrical body fixed to the mounting member 142 with a pair offasteners 152. In the form illustrated, the fasteners 152 includethreaded fasteners. Similar to the mounting member 142, the diskretainer 144 defines a through-bore 154. The through-bore 154 of thedisk retainer 144 has a diameter substantially identical to a diameterof the through-bore 150 in the mounting member 142 and is axiallyaligned therewith.

As depicted, the disk retainer 144 secures the disk holder 146 and thesealing disk 148 to the mounting member 142 of the retainer assembly132. The disk holder 146 includes a generally ring-shaped plateconstructed of a rigid material such as steel. The sealing disk 148includes a generally ring-shaped disk made of a resilient material andfixed to the disk holder 146. In one form, the sealing disk 148 is fixedto the disk holder 146 with an adhesive. In accordance with thedisclosed form, the configuration of the disk retainer 144 limits radialdeformation of the sealing disk 148 when the control assembly 114 is ina closed position and compressing the sealing disk 148 against the seatring 104.

Referring now to the upper portion of the regulator 100 depicted in FIG.2, the diaphragm subassembly 133 includes a diaphragm 134, an upperdiaphragm plate 136 a and a lower diaphragm plate 136 b. The upper andlower diaphragm plates 136 a, 136 b are clamped onto the circumferentialflange 140 of the sleeve 130. The diaphragm plates 136 a, 136 b aresecured together via fasteners 156, thereby fixing the sleeve 130 andthe diaphragm plates 136 a, 136 b together. Additionally, the diaphragmplates 136 a, 136 b sandwich a radially inward portion of the diaphragm134. A radially outward portion of the diaphragm 134 is fixed betweenthe upper and lower actuator casings 122, 124.

The positioning device assembly 138 is primarily disposed within thesleeve 130 to bias the sleeve 130 into the open position depicted inFIG. 2. The positioning device assembly 138 generally comprises acentral rod 186, a first spring seat 188, a second spring seat 190, aspring 193, and a retention plate 192. The central rod 186 includes afirst threaded end 186 a and a second threaded end 186 b. The firstthreaded end 186 a extends through the central opening 123 of the upperactuator casing 122. An external nut 194 is threaded onto the firstthreaded end 186 a to limit axial displacement of the central rod 186 inthe downward direction relative to the orientation of the actuator 100depicted in FIG. 2. An intermediate nut 196 is threaded onto the firstthreaded end 186 a of the central rod 186 beyond the external nut 194 tolimit axial displacement of the central rod 186 in the upward directionrelative to the orientation of the actuator 100 depicted in FIG. 2.Accordingly, the first threaded end 186 a of the central rod 186 iseffectively fixed against axial displacement relative to the upperactuator casing 122 and the second threaded end 186 b extends into theactuator 106.

Accordingly, as depicted, the second threaded end 186 b of the centralrod 186 extends into the sleeve 130 and is disposed adjacent the secondend 130 b of the sleeve 130. A pair of retention nuts 198 a, 198 b arethreaded onto the second threaded end 186 b of the central rod 186. Theretention nuts 198 a, 198 b support the first spring seat 188, thespring 193, and the second spring seat 192 on the central rod 186. Thefirst spring seat 188 is slidably disposed within the sleeve 130, aswill be discussed in more detail below. More specifically, the firstspring seat 188 comprises a generally cylindrical plate in engagementwith the retention nuts 198 a, 198 b. The spring 193 therefore fixes thesecond spring seat 192 against the retention plate 192, and relative tothe sleeve 130. Moreover, the first spring seat 188 is fixed relative tothe central rod 186 and defines a central opening 188 a and a pluralityof apertures 188 b. The central opening 188 a receives the second end186 b of the central rod 186 directly adjacent the retention nuts 198 a,198 b. The plurality of apertures 188 b are in fluid communication withthe through-bores 150, 154 in the mounting subassembly 132, andtherefore the flow-path 108.

Similarly, the second spring seat 190 comprises a generally cylindricalplate defining a central opening 190 a and a plurality of apertures 190b. The central opening 190 a in the second spring seat 190 receives thecentral rod 186 near the first threaded end 186 a. The plurality ofapertures 190 b are in fluid communication with the plurality ofapertures 188 b in the first spring seat 188, and therefore theflow-path 108. Accordingly, as depicted, the spring 193 is disposedaxially between and in engagement with the first spring seat 188 and thesecond spring seat 190. The first spring seat 188, which is fixed by theretention nuts 198 against displacement in the downward directionrelative to the central rod 186, supports the spring 193. Thus, thespring 193 supports the second spring seat 190.

Moreover, the retention plate 192 comprises a generally cylindricalplate defining a central opening 192, a plurality of apertures 192 b,and a threaded portion 195. The threaded portion 195 of the retentionplate 192 is fixed by threaded engagement with the threaded portion 141on the inner surface 143 of the sleeve 130. Accordingly, the retentionplate 192 and the sleeve 130 act as a unitary structure.

During assembly, with the upper actuator casing 122 removed from thelower actuator casing 124 and the sleeve 130 removed from between thediaphragm plates 136 a, 136 b, the retention plate 192 is threaded intothe threaded portion 141 of the sleeve 130. Subsequently, theintermediate nut 196 is threaded onto the first threaded end 186 a ofthe central rod 186. The second threaded end 186 b of the central rod186 is then disposed through the central opening 192 a of the retentionplate 192. Next, with the central rod 186 in place, the second springseat 190, the spring 193, and the first spring seat 188 are slid ontothe central rod 186, in that order, via the opening in the lower portion130 b of the sleeve 130. The retention nuts 198 a, 198 b are thenthreaded onto the second threaded end 186 b of the central rod 186, asdepicted.

At this point, a technician or engineer may preload the positioningdevice assembly 138 by tightening either the intermediate nut 196disposed adjacent the retention plate 192 or the retention nuts 198 a,198 b disposed adjacent the first spring seat 188. For example,tightening the intermediate nut 196 pulls the central rod 186 throughthe second spring seat 190 and the retention plate 192. This causes theretention nuts 198 a, 198 b to apply an axial force to the first springseat 188 and displace the first spring seat 188 toward the second springseat 190. Continued tightening of the intermediate nut 196 compressesthe spring 193 between the first and second spring seats 188, 190.

Alternatively, tightening the retention nuts 198 a, 198 b disposedadjacent the first spring seat 188 forces the first spring seat 188toward the second spring seat 190 to compress the spring 193. It shouldbe appreciated that in the depicted embodiment, the retention nuts 198a, 198 b comprise a first retention nut 198 a disposed directly adjacentthe first spring seat 188 and a second retention nut 198 b disposeddirectly adjacent the first retention nut 198 a opposite the firstspring seat 188. Accordingly, in the above-described preloadingoperation, a technician or engineer would first tighten the firstretention nut 198 a to displace the first spring seat 188 to compressthe spring 193. Subsequently, the technician or engineer would tightenthe second retention nut 198 b into engagement with the first retentionnut 198 a to effectively lock the first retention nut 198 a in place onthe central rod 186.

Additionally, it should be appreciated that in one embodiment of thepositioning device assembly 138 disclosed herein, the central rod 186may comprise markings along the lengths of at least one of the threadedportions 186 a, 186 b, such that the technician or engineer performingeither of the above-described pre-loading operations may tighten theintermediate nut 196 or the retention nuts 198 a, 198 b to apredetermined position on the central rod 186, thereby pre-loading thespring 193 a predetermined amount.

With the positioning device assembly 138 appropriately pre-loaded, thecircumferential flange 40 of the sleeve 130 is coupled into thediaphragm plates 136 a, 136 b and the lower portion 130 b of the sleeve130 is disposed within the neck 128 of the lower actuator casing 124.The upper actuator casing 122 is then positioned onto the lower actuatorcasing 124 such that the first threaded end 186 of the central rod 186is disposed through the central opening 123. A technician or engineercan then secure the upper actuator casing 122 to the lower actuatorcasing 124 with the threaded fasteners 119. Finally, the technician orengineer tightens the external nut 194 onto the first threaded end 186 aof the central rod 186. Tightening the external nut 194 pulls thecentral rod 186, and therefore the intermediate nut 196 and the firstspring seat 188 upward relative to the orientation of the regulator 100depicted in FIG. 2. The external nut 194 and the intermediate nut 196sandwich the upper actuator casing 122, as depicted. So configured, theexternal nut 194 and the intermediate nut 196 fix the central rod 186against axial displacement relative to the upper actuator casing 122.Additionally, the retention nuts 198 a, 198 b fix the first spring seat188 against axial displacement in the downward direction relative to theorientation of the regulator 100 depicted in FIG. 2.

In general, when the regulator assembly 100 is installed within a fluidprocess control or fluid delivery system, the control assembly 114 isable to reciprocally displace within the cavity 135 and hollow neck 128of the actuator 106 based on the pressure of the fluid at the inlet 110and outlet 112 of the valve body 102. Specifically, fluid flows from theinlet 110 and through the throat 116. Once the fluid passes through thethroat 116, a substantial portion of the fluid flows to the outlet 112,while the remainder flows through the through-bores 150, 154 in themounting member 142 and disk retainer 144, respectively. That portion ofthe fluid continues to flow through the sleeve 130 via the apertures 188b, 190 b, 192 b in the first and second spring seats 188, 190 andretention plate 192, respectively, to balance the control assembly 114.In the disclosed embodiment, the apertures 190 b in the second springseat 190 are substantially aligned with the apertures 192 b in theretention plate 192. This ensures that pressurized fluid travelingthrough the regulator 100 can pass through the apertures 190 b, 192 bwithout obstruction to balance the control assembly 114. In oneembodiment, one of the second spring seat 190 and the retention plate192 may include a dimple on an axially disposed surface thereof. Theother of the second spring seat 190 and retention plate 192 may includea recess for receiving the dimple. The recess would only receive thedimple when the second spring seat 190 and retention plate 192 areproperly aligned to permit fluid communication between the apertures 190b, 192 b, as depicted. Alternatively, in another embodiment the secondspring seat 190 and retention plate 192 may comprise a single unitarymember, thereby alleviating the need for specific alignment. In yetanother alternative embodiment, the apertures 190 b and 192 b maycomprise elongated apertures extending at least partiallycircumferentially about the spring seat 190 and the retention plate 192.So configured, the second spring seat 190 and retention plate 192 may bearranged in a plurality of relative positions and still provide thenecessary fluid communication between the apertures 190 b, 192 b.

The portion of the fluid that flows through the valve body 102 and tothe outlet 112 flows back into the fluid process control or fluiddelivery system. Specifically, in one form, the pressure of the fluid atthe outlet 112 is bled off into another fluid line (not shown) anddirected to the second control inlet 129 in the lower actuator casing124. Hence, the pressure at the outlet 112 of the valve body 102 equalsthe pressure at the second control inlet 129, which is ultimatelyapplied to the lower diaphragm plate 136 b. Additionally, in one form,the pressure at the inlet 110 is bled off into another fluid line to apilot valve (not shown) and further directed to the first inlet control125 in the upper actuator casing 122.

Therefore, when the pressure at the first control inlet 125 applies aforce to the upper diaphragm plate 136 a that is greater than a forceapplied by the pressure at the second control inlet 129 in combinationwith the positioning device assembly 138 and, more particularly, thespring 193 of the positioning device assembly 138, the diaphragm plates136 a, 136 b and the control sleeve 130 displace downward against thebias of the spring 138. More specifically, the diaphragm plates 136 a,136 b and the sleeve 130, as well as the retention plate 192 and thesecond spring seat 190 of the positioning device assembly 138 displacedownward. This downward displacement compresses the spring 193 towardthe first spring seat 188. Hence, it should be appreciated that as thesleeve 130 slidably displaces downward, the central rod 186 and thefirst spring seat 188 remain in the position depicted in FIG. 2, whilethe sleeve 130, retention plate 192, and second spring seat 190 displacedownwardly.

Alternately, when the pressure at the second control inlet 129 incombination with the spring 193 applies a force to the control assembly114 that is greater than the pressure at the first control inlet 125,the control assembly 114 displaces upward toward the open positiondepicted in FIG. 2. The sum of the upward forces acting on the diaphragmis opposed by the pressure at the first control inlet 125, which servesas a controlling pressure, to position the control assembly 114including the sleeve 130 according to the flow required to meet adownstream demand. Additionally, if the diaphragm 134 happened to faildue to a tear in the diaphragm material, for example, the spring 193would apply a force on the second spring seat 190, which, in turn,forces the control assembly 114 to the open position depicted in FIG. 2.

While the regulator 100 has just been described as comprising a “failopen” regulator, the positioning device assembly 138 in accordance withan alternative embodiment of the regulator 100 may be configured todefine a “fail close” regulator. For example, in such an alternativeembodiment, the first spring seat 188 may be fixed to the inner surface143 of the sleeve 130 and the second spring seat 190 may be fixed to theelevator rod 186. So configured, the spring 193 disposed between thefirst and second spring seats 188, 190 would bias the first spring seat188 away from the second spring seat 190, thereby biasing the sleeve 130in a downward direction relative to the orientation of the regulator 100depicted in FIG. 2. Furthermore, the spring 193 could be pre-loadedaccording to either of the above-described pre-loading operations suchthat in the absence of pressure in the actuator 106 or upon a failure ofthe diaphragm 134, the spring 193 would force the sleeve 130 to closethe flow of fluid to the outlet 112.

While the control assembly 114 depicted in FIG. 2 may be pre-loadedaccording to either of the two pre-loading operations discussed above,an alternative embodiment of the control assembly may include shoulders,for example, disposed on opposite ends of the central rod 186 fordefining a pre-loaded condition of the assembly. The particular positionof the shoulders formed on the central rod 186 would be predeterminedbased on a predetermined amount of pre-loading required for a desiredapplication.

FIG. 3 illustrates one such alternative control assembly 314. Similar tothe control assembly 114 disclosed in FIG. 2, the control assembly 314includes a control member such as a hollow sleeve 330, a mountingsubassembly 332, a diaphragm subassembly 333, which is only partiallyillustrated and generally identical to the diaphragm subassembly 133disclosed in FIG. 2, and a positioning device assembly 338. The sleeve330 is generally tubular defining a generally cylindrical inner surface343 and a generally cylindrical outer surface 347. The inner surface 343defines a central bore through the sleeve 330. Additionally, the sleeve330 includes an upper end 330 a and a lower end 330 b. The sleeve 330 isslidably disposed within an actuator 306, which includes upper and loweractuator casings 322, 324 (shown fragmented) and is generally identicalto the actuator 106 disclosed in FIG. 2. The upper end 330 a of thesleeve 330 is open and includes a circumferential flange 340 formed onthe outer surface 347. Additionally, the upper portion 330 a of thesleeve 330 includes a threaded portion 341 on the inner surface 343. Thelower end 330 b of the sleeve 330 is open and accommodates the mountingsubassembly 332, the details of which are identical to the mountingsubassembly 132 disclosed in FIG. 2 and, therefore, will not berepeated.

Similar to the positioning device assembly 138 described above, thepositioning device assembly 338 is primarily disposed within the sleeve330 to bias the sleeve 330 upward, relative to the actuator casings 322,324. The positioning device assembly 338 generally comprises a centralrod 386, a first spring seat 388, a second spring seat 390, and a spring393. The central rod 386 includes a first threaded end 386 a, a secondthreaded end 386 b, and an increased diameter portion 386 c disposedbetween the first and second threaded ends 386 a, 386 b. The increaseddiameter portion 386 c defines an upper shoulder 396 adjacent the firstthreaded end 386 a and a lower shoulder 399 adjacent the second threadedend 386 b. The first threaded end 386 a extends through a centralopening 323 in the upper actuator casing 322. An external nut 394 isthreaded onto the first threaded end 386 a and engages the upperactuator casing 322 to limit axial displacement of the central rod 386in the downward direction relative to the orientation of the actuator306 depicted in FIG. 3. The upper shoulder 396 of the central rod 386engages the upper actuator casing 322 opposite the external nut 394 andlimits axial displacement of the central rod 386 in the upward directionrelative to the orientation of the actuator 306 depicted in FIG. 3. Inthe disclosed embodiment, the upper shoulder 396 accommodates an o-ring397 to provide a fluid-tight seal with the upper actuator casing 322 toprevent fluid from leaking out of the central opening 323. Accordingly,the first threaded end 386 a of the central rod 386 is effectively fixedto the upper actuator casing 322 and the second threaded end 386 bextends into the actuator 306.

As depicted, the second threaded end 386 b of the central rod 386extends into the sleeve 330 and is disposed adjacent the second end 330b of the sleeve 330. A retention nut 398 is threaded onto the secondthreaded end 386 b of the central rod 386. The first spring seat 388 isslidably disposed within the sleeve 330. More specifically, the firstspring seat 388 comprises a generally cylindrical plate defining acentral opening 388 a, a plurality of apertures 388 b, a stepped portion388 c, and an annular recess 388 d that receives a guide ring 389. Thecentral opening 388 a receives the second threaded end 386 b of thecentral rod 386, and the retention nut 398 fixes the first spring seat388 against the lower shoulder 399 of the central rod 386. The pluralityof apertures 188 b are in fluid communication with a flow path throughthe regulator, as described above with reference to the first springseat 188 disclosed in FIG. 2.

The second spring seat 390 comprises a generally cylindrical platedefining a central opening 390 a, a plurality of apertures 390 b, astepped portion 388 c, and a threaded portion 388 d. The central opening390 a in the second spring seat 390 receives the increased diameterportion 286 c of the central rod 386 near the first threaded end 386 a.The threaded portion 388 d is in threaded engagement with the threadedportion 341 of the sleeve 330, thereby fixing the second spring seat 390to the sleeve 300. The plurality of apertures 390 b are in fluidcommunication with the plurality of apertures 388 b in the first springseat 388, and therefore the flow-path through the regulator.

Accordingly, as depicted, the spring 393 is disposed axially between andin engagement with the first spring seat 388 and the second spring seat390. More specifically, in the disclosed embodiment, the spring 393 issupported between the stepped portions 388 c, 390 c of the first andsecond spring seats 388, 390, which help maintain the alignment of thespring 393 relative to the other components.

During assembly, with the upper actuator casing 322 removed from thelower actuator casing 324 and the sleeve 330 removed from the actuator306, a technician threads the second spring seat 390 into engagementwith the threaded portion 341 on the upper end 330 a of the sleeve 330.In one embodiment, an adhesive such as Loctite 242 may be applied to thethreaded portion 341 of the sleeve and/or the threaded portion 388 d ofthe second spring seat 390 prior to threading the two componentstogether. Next, the o-ring 397 is lubricated and positioned within theshoulder 396 of the central rod 386, as depicted in FIG. 3. The centralrod 386 is then disposed through the central opening 390 a in the upperspring seat 390 such that the increased diameter portion 386 c isdisposed within the sleeve 300, as depicted. The spring 393 is theninserted through the lower end 330 b of the sleeve 330 and positionedaround the stepped portion 390 c of the second spring seat 390. With thespring 393 in position, the first spring seat 388 is inserted onto thesecond threaded end 386 b of the central rod 386. Prior to positioningthe first spring seat 388, however, the technician may be required toposition the guide ring 389 within the annular recess 388 d in the firstspring seat 388. Nevertheless, with the first spring seat 388 inposition on the second threaded end 386 b of the central rod 386, theretention nut 398 is threaded onto the second threaded end 386 a andtightened against the first spring seat 388 such that the steppedportion 388 c of the first spring seat 388 engages the lower shoulder399 of the central rod 386 and receives the spring 393, as depicted. Inone embodiment, the spring 393 compress, and is therefore pre-loaded,approximately one inch (1″) before the spring seat 388 engages theshoulder 399. With the positioning device assembly 338 assembled, it isinserted into the removed upper actuator casing 322 such that the firstthreaded end 386 a of the central rod 386 is disposed through thecentral opening 323. So configured, the external nut 394 is threadedonto the first threaded end 386 a and the central rod 386 is therebyfixed to the upper actuator casing 322. Finally, the control assembly314 is inserted into the lower actuator casing 324 and the upperactuator casing 322 is affixed thereto with bolts, or some otherconventional means.

It should be appreciated that the control assembly 314 disclosed in FIG.3 operates substantially similarly to the control assembly 114 disclosedwith reference to FIG. 2, and therefore, the details of such operationwill not be repeated.

While the control assembly 314 disclosed in FIG. 3 includes a singlecentral rod 386, one alternative embodiment of a control assembly 314constructed in accordance with the present invention may comprisemultiple central rods 386, each having shoulders 396, 399 positioned atdifferent locations such that a technician or engineer may pre-selectthe appropriate central rod 386 to pre-load the spring 393 a particularamount for a particular application.

FIG. 4 depicts an alternative embodiment of a regulator 200 constructedaccording to the principles of the present disclosure. The regulator 200depicted in FIG. 4 is substantially similar to the regulator 100described above with reference to FIG. 2 in that the regulator 200generally comprises a valve body 202 and an actuator 206. The valve body202 defines a flow-path 208 extending between an inlet 210 and an outlet212, as well as into the actuator 206. The actuator 206 includes acontrol assembly 214 that is moveable between an open position, as isshown in FIG. 4, and a closed position (not shown). Movement of thecontrol assembly 214 occurs in response to fluctuations in the pressureof the fluid at the inlet 210 and outlet 212 of the valve body 202.Accordingly, the position of the control assembly 214 relative to theseat ring 204 effects a flow capacity of the pressure regulator 200. Ingeneral, the valve body 202 and actuator 206 are identical to the valvebody 102 and the actuator 106 described above with reference to FIG. 2,and therefore only the distinctions will be described in detail.

For example, the control assembly 214 comprises a sleeve 230, a mountingsubassembly 232, a diaphragm subassembly 233, and a positioning deviceassembly 238. The sleeve 230, mounting subassembly 232, and diaphragmsubassembly 233 are identical to those described above. The positioningdevice assembly 238, however, is distinct from the positioning deviceassembly 138 described above.

The positioning device assembly 238 depicted in FIG. 4 is primarilydisposed outside of the sleeve 230, as well as the actuator 206, andadjacent the upper actuator casing 222. The positioning device assembly238 generally comprises a central rod 286, a first spring seat 288, asecond spring seat 290, a spring 293, a retention plate 292, a sealassembly 296, and an enclosure 297.

The second spring seat 290 comprises a generally cylindrical plateincluding a central opening 290 a, a cylindrical flange portion 291, andan external threaded portion 293. The first spring seat 288 comprises agenerally cylindrical plate including a central opening 288 a and acylindrical flange portion 289. The spring 293 of the depicted formcomprises a coil spring disposed concentrically around the central rod286 and axially between the first and second spring seats 288, 290. Thecylindrical flange portions 289, 291 of the first and second springseats 288, 290, respectively, retain the spring 293 between the springseats 288, 290.

The second spring seat 290 is fixed relative to and disposed inengagement with an external surface of the upper actuator casing 222such that the central opening 290 a is generally axially aligned withthe opening 223 in the upper actuator casing 222. The spring 293 isaxially disposed upon the second spring seat 290. The first spring seat288 is axially disposed upon the spring 293 opposite the second springseat 290. A first retention nut 294 is threaded onto a first threadedend 286 a of the central rod 286 adjacent the first spring seat 288. Thefirst retention nut 294 retains the relative axial disposition of thespring 293, the first spring seat 288, and the second spring seat 290.So configured, the first spring seat 288 is fixed relative to thecentral rod 286. The enclosure 297 comprises a generally elongatedtubular structure having an internal threaded portion 297 a. Thethreaded portion 297 a of the enclosure 297 is in threaded engagementwith the threaded portion 293 of the second spring seat 290.

Similar to that described above with reference to the regulator 100depicted in FIG. 2, the retention plate 292 comprises a generallycylindrical plate defining a central opening 292 a, a plurality ofapertures 292 b, and an external threaded portion 295. The threadedportion 295 is in threaded engagement with a threaded portion 241 on aninner surface 243 of the sleeve 230, thereby fixing the retention plate292 to the sleeve 230. The apertures 292 b are in fluid communicationwith through-bores 250, 254 in the mounting subassembly 232, andtherefore the flow-path 208. The central opening 292 a receives a secondthreaded end 286 b of the central rod 286. A second retention nut 298 isin threaded engagement with the second threaded end 286 b of the centralrod 286 adjacent the retention plate 292. Accordingly, the secondretention nut 298 fixes the retention plate 292 against displacementrelative to the central rod 286 in the downward direction relative tothe orientation of the regulator 200 depicted in FIG. 4.

The seal assembly 296 is disposed within a central opening 223 of theupper actuator casing 222. The seal assembly 296 provides a fluid tightseal between the central rod 286 and the upper actuator casing 222. Inthe embodiment depicted in FIG. 4, the seal assembly comprises a bushing296 a, a pair of grommets 296 b, and an o-ring 296 c. The bushing 296 ais fixed within the central opening 223 and locates the grommets 296 band the o-ring 296 c. The grommets 296 b provide a sliding seal suchthat bi-directional displacement of the central rod 286 relative to theupper actuator casing 222 does not leak the pressure in the sleeve 230.The o-ring 296 c is disposed between the bushing 296 a, the upperactuator casing 222, and the second spring seat 290. The o-ring 296 cforms a fluid tight seal between the bushing 296 a and the upperactuator casing 222. In one embodiment, the bushing 296 a is constructedof a semi-rigid or rigid polymer, while the grommets 296 b and theo-ring 296 c are constructed of a resilient material such as anelastomer or a rubber. It should be appreciated that while the centralopening 223 in the upper actuator casing 222 depicted in FIG. 4 isslightly larger than a diameter of the central opening 123 in the upperactuator casing 122 of the regulator 100 depicted in FIG. 2, suchdepiction is merely schematic and alternative embodiments may includethe same diameter central openings. For example, in one embodiment, adiameter of the central rod 286 of FIG. 4 may be reduced, therebyallowing for a smaller central opening 223 capable of accommodating boththe central rod 286 and the seal assembly 296.

During assembly, with the upper actuator casing 222 removed from thelower actuator casing 224 and the sleeve 230 removed from betweendiaphragm plates 236 a, 236 b, the retention plate 292 is threaded intothe threaded portion 241 of the sleeve 230. Subsequently, the secondretention nut 298 is threaded onto the second threaded end 286 b of thecentral rod 286. The first threaded end 286 a of the central rod 286 isthen disposed through the central opening 292 a of the retention plate292 via the lower end 230 b of the sleeve 230. Next, the seal assembly296 is secured within the central opening 223 of the upper actuatorcasing 222. Then, the first threaded end 286 a of the central rod 286 isdisposed through the seal assembly 296 such that the retention plate 292engages the upper actuator casing 222, as depicted in FIG. 4. With thecentral rod 286 positioned relative to the upper actuator casing 222,the second spring seat 290, the spring 293, and the first spring seat288 are slid onto the first threaded end 286 a of the central rod 286,in that order. The first retention nut 294 is then threaded onto thefirst threaded end 286 a of the central rod 286 to secure the springseats 288, 290 and spring 293 onto the central rod 286. The sleeve 230may then be secured between the diaphragm plates 236 a, 236 b and theupper actuator casing 222 secured to the lower actuator casing 224.

At this point, a technician or engineer may preload the positioningdevice assembly 238 by tightening the retention nut 294 disposedadjacent the first spring seat 288 on the first threaded end 286 a ofthe central rod 286. For example, tightening the retention nut 294forces the first spring seat 288 downward relative to the orientation ofthe regulator 200 depicted in FIG. 4. This causes the first spring seat288 to compress the spring 293 against the second spring seat 290,thereby pre-loading the control assembly 214.

Alternatively, prior to securing the sleeve 230 between the diaphragmplates 236 a, 236 b, a technician or engineer may tighten the secondretention nut 298 disposed adjacent the retention plate 292 within thesleeve 230 to pre-load the spring 293. Doing so, however, would requirea tool such as an elongated socket capable of reaching and/or extendingfrom the lower end 230 b of the sleeve 230 to the upper end 230 a of thesleeve 230. Nevertheless, in either of the above-described pre-loadingoperations for the positioning device assembly 238, compressing thespring 293 a predetermined amount provides a predetermined amount ofpre-load for acting on the retention plate 292 to bias the sleeve 230into the open position depicted in FIG. 4.

Additionally, it should be appreciated that in one embodiment of thepositioning device assembly 238, the central rod 286 may comprisemarkings along the lengths of one or both of the first and secondthreaded ends 286 a, 286 b such that the technician or engineerperforming the pre-loading operation may tighten the appropriateretention nut 294, 298 to a predetermined position on the central rod286. In another embodiment, the first and/or second threaded ends 286 a,286 b of the central rod 286 may include shoulders, at which the threadson the threaded ends 286 a, 286 b terminate. The particular position ofthe shoulders formed on the central rod 286 would be predetermined basedon a predetermined amount of preloading required for a desiredapplication of the regulator 200. Accordingly, during the pre-loadingoperation, the technician or engineer may tighten either or both of theretention nuts 294, 298 into engagement with the respective shoulder.One embodiment of the regulator 200 and/or the positioning deviceassembly 238 may comprise multiple central rods 286 such that thetechnician or engineer may pre-select the appropriate central rod 286having shoulders specifically positioned to pre-load the spring 293 aparticular amount for a particular application.

With the positioning device assembly 238 of the embodiment depicted inFIG. 4 appropriately preloaded, the threaded portion 297 a of theenclosure 297 is threaded into engagement with the threaded portion 293of the second spring seat 290. The enclosure 297 therefore protects thespring seats 288, 290, the central rod 286, the spring 293, and the sealassembly 296 from collecting dirt, dust, debris, moisture, or any othermaterial, as well as from damage caused by potential impact.

In general, when the regulator assembly 200 is installed within a fluidprocess control or fluid delivery system, the control assembly 214 isable to reciprocally displace within a cavity 235 and a hollow neck 228of the actuator 206 according to the pressures at the inlet 210 andoutlet 212 of the valve body 202. Specifically, fluid flows from theinlet 210 of the valve body 202 and through the throat 216. Once thefluid passes through the throat 216, a substantial portion of the fluidflows to the outlet 212 while the remainder flows into the sleeve 230 ina manner similar to that described above with respect to the regulator100 depicted in FIG. 2. That portion of the fluid flows through thesleeve 230 including through the apertures 292 b in the retention plate292, thereby balancing the control assembly 214. Therefore, it should beappreciated that the pressure engages the portion of the seal assembly296 exposed to the cavity 235 of the actuator 206. As mentioned above,however, the bushing 296 a in combination with the grommets 296 b andthe o-ring 296 c prevent any pressure loss to occur between the centralopening 223 and the central rod 286.

The portion of the fluid that flows through the valve body 202 and tothe outlet 212 flows back into the fluid process control system.Specifically, in one form, the pressure of the fluid at the outlet 212is bled off into another fluid line (not shown) and directed to a secondcontrol inlet 229 in the lower actuator casing 224. Hence, the pressureat the outlet 212 of the valve body 202 equals the pressure at thesecond control inlet 229, which is ultimately applied to the lowerdiaphragm plate 236 b. Additionally, in one form, the pressure at theinlet 210 is bled off into another fluid line to a pilot valve (notshown) and further directed to a first control inlet 225 in the upperactuator casing 222.

Therefore, when the pressure at the first control inlet 225 applies aforce to the upper diaphragm plate 236 a that is greater than a forceapplied by the pressure at the second control inlet 229 in combinationwith the positioning device assembly 238 and, more particularly, thespring 293 of the positioning device assembly 238, the diaphragm plates236 a, 236 b and the sleeve 230 displace downward against the bias ofthe spring 238. More specifically, the diaphragm plates 236 a, 236 b andthe sleeve 230, as well as the retention plate 292, the central rod 286,and the first spring seat 288 of the positioning device assembly 238displace downward. This downward displacement compresses the spring 293toward the second spring seat 290 beyond its pre-loaded amount. Hence,it should be appreciated that as the sleeve 230 slidably displacesdownward in the cavity 235, the central rod 286 slidably and sealinglydisplaces through the seal assembly 296 disposed in the central opening223 of the upper actuator casing 222 and the second spring seat 290remains fixed in the position depicted in FIG. 4.

Alternately, when the pressure at the second control inlet 229 incombination with the spring 293 applies a force to the control assembly214 that is greater than the pressure at the first control inlet 225,the control assembly 214 displaces upward toward the open positiondepicted in FIG. 4. More specifically, the sleeve 230, the diaphragmplates 236 a, 236 b, and the retention plate 292 of the control assembly214, as well as the central rod 286 and the first spring seat 288 of thepositioning device assembly 238, displace to the position illustrated inFIG. 4. The sum of the upward forces acting on the diaphragm subassembly233 is opposed by the pressure at the first control inlet 225, whichserves as a controlling pressure, to position the control assembly 214including the sleeve 230 according to the flow required to meet thedownstream demand. Additionally, if the diaphragm 234 happened to faildue to a tear in the diaphragm material, for example, the spring 293 ofthe positioning device assembly 238 would apply a force to the firstspring seat 288, which, in turn, applies a force to the central rod 286and the retention plate 292, to force the sleeve 130 of the controlassembly 214 to the open position depicted in FIG. 4.

While the regulator 200 has just been described as comprising a “failopen” regulator, the positioning device assembly 238 in accordance withan alternative embodiment of the regulator 200 may be configured todefine a “fail close” regulator. For example, in such an alternativeembodiment, the first spring seat 288 would be fixed to the enclosure297. Additionally, the central rod 286, the second spring seat 290, theretention plate 292, and the sleeve 230 would all be rigidly fixedtogether. The second spring seat 290 would also be freely axiallydisplaceable within the enclosure 297, as opposed to being in threadedengagement with the enclosure 297.

So configured, the spring 293 disposed between the first and secondspring seats 288, 290 would bias the second spring seat 290 away fromthe first spring seat 288, thereby biasing the central rod 286, theretention plate 292, and the sleeve 230 in a downward direction relativeto the orientation of the regulator 200 depicted in FIG. 4. Furthermore,the spring 293 could be pre-loaded according to either of theabove-described pre-loading operations such that in the absence ofpressure in the actuator 206 or upon failure of the diaphragm 234, thespring 293 would force the sleeve 230 to close the flow of fluid to theoutlet 212. In one embodiment of this “fail close” configuration, theretention plate 292 would be secured adjacent the lower end 230 b of thesleeve 230. Accordingly, the central rod 286 would be linearly displacedrelative to that depicted in FIG. 4 such that a majority thereof wouldbe disposed in the sleeve 230. More specifically, in one embodiment, thefirst threaded end 286 a of the threaded rod 286 could be in threadedengagement with the central opening 290 a of the second spring seat 290.Similarly, the first threaded end 286 a of the central rod 286 could bein threaded engagement with the central opening 292 a in the retentionplate 292.

Accordingly, in light of the foregoing, it should be appreciated thatthe present disclosure provides for a fluid regulator that is operablein a “fail open” or “fail close” configuration. More specifically, thepresent disclosure provides a control assembly 114, 214, 314 that isadaptable to a conventional “fail close” regulator, such as thatdepicted and described with reference to FIG. 1, without requiring anystructural modification or redesigning of the existing component of theconventional regulator 10. Furthermore, the present disclosure providesfor a positioning device assembly 138, 238, 338 operable to bias acontrol member such as a sleeve 130, 230, 330 of a regulator 10, 100,200 into a predetermined position within the actuator 106, 206, 306and/or valve body 102, 202, 302 with which the control assembly 114,214, 314 is associated. The predetermined position may include the “failopen” or the “fail close” positions described herein or may include anyother position that may be desired for a particular application andwhich is located between the “fail open” and “fail close” positions.

Finally, it should be appreciated that while the present disclosure hasbeen provided in the context of a pressure regulator, it may besuccessfully incorporated into other fluid process control devicesincluding control valves, actuators, and any other foreseeable device.

In light of the foregoing, the description of the present disclosureshould be understood as merely providing examples of the presentinvention and, thus, variations that do not depart from the gist of theinvention are intended to be within the scope of the invention.

What is claimed:
 1. A control assembly for regulating the flow of afluid through a fluid flow-path of a regulator, the control assemblycomprising: a control member; a diaphragm subassembly connected to thecontrol member and including a diaphragm, the diaphragm extendingradially outward from the control member and adapted to respond topressure changes on opposing sides thereof for moving the control memberwhen installed within a regulator; a central rod adapted to be disposedthrough a casing of the regulator; a first spring seat defining anopening receiving the central rod, the first spring seat fixed relativeto the central rod; a second spring seat defining an opening receivingthe central rod, the second spring seat fixed relative to the regulatorcasing; a spring disposed between the first and second spring seats, thespring biasing the control member into a predetermined position relativeto the regulator casing; a retention plate fixed relative to the controlmember and the central rod, wherein the retention plate is adapted to bedisposed in the fluid flow-path of the regulator and defines an aperturein fluid communication with the fluid flow path.
 2. The control assemblyof claim 1, wherein the first spring seat, the second spring seat, andthe spring are disposed outside of the control member.
 3. The controlassembly of claim 1, wherein the control member comprises a hollowtubular sleeve.
 4. The control assembly of claim 1, wherein theretention plate is disposed inside of the control member.
 5. The controlassembly of claim 1, wherein the diaphragm subassembly comprises upperand lower diaphragm plates sandwiching at least a portion of thediaphragm.
 6. A regulator, comprising: a valve body defining a flow-pathfor a fluid; an actuator casing coupled to the valve body; a controlmember disposed within the actuator casing and adapted for displacementrelative to the valve body for regulating a flow of the fluid throughthe flow-path; a diaphragm subassembly connected to the control memberand including a diaphragm, the diaphragm extending radially outward fromthe control member and adapted to respond to pressure changes onopposing sides thereof for moving the control member in the actuatorcasing; a central rod disposed through the actuator casing; a firstspring seat fixed relative to the central rod; a second spring seatfixed relative to the actuator casing; a spring disposed between thefirst spring seat and the second spring seat, the spring biasing thecontrol member into a predetermined position within the casing of theregulator; and a retention plate fixed relative to the control memberand the central rod, wherein the retention plate is disposed in thefluid flow-path of the regulator and defines an aperture in fluidcommunication with the fluid flow-path.
 7. The regulator of claim 6,wherein the first spring seat, the second spring seat, and the springare disposed outside of the control member, and the second spring seatis fixed relative to the regulator casing.
 8. The regulator of claim 6,further comprising a valve seat carried by the valve body, wherein thespring biases the control member away from the valve seat.
 9. Theregulator of claim 6, wherein the control member comprises a hollowtubular sleeve.
 10. The regulator of claim 6, wherein the retentionplate is disposed inside of the control member.
 11. The regulator ofclaim 6, wherein the diaphragm subassembly comprises upper and lowerdiaphragm plates sandwiching at least a portion of the diaphragm.
 12. Aregulator, comprising: a valve body defining a flow-path for a fluid; anactuator casing coupled to the valve body; a control member disposedwithin the actuator casing and adapted for displacement relative to thevalve body for regulating a flow of the fluid through the flow-path; adiaphragm subassembly connected to the control member and including adiaphragm, the diaphragm extending radially outward from the controlmember and adapted to respond to pressure changes on opposing sidesthereof for moving the control member in the actuator casing; apositioning device assembly comprising a central rod and a springdisposed about the central rod, at least a portion of the central roddisposed within the control member, the spring disposed outside of thecontrol member and biasing the control member into a predeterminedposition relative to the valve body, wherein the positioning deviceassembly further comprises: a first spring seat fixed relative to thecentral rod; and a second spring seat fixed relative to the actuatorcasing, wherein the spring is disposed between the first and secondspring seats, wherein the first spring seat, the second spring seat, andthe spring are disposed outside of the control member; and a retentionplate fixed relative to the control member and the central rod, theretention plate disposed in the fluid flow-path of the regulator anddefining an aperture in fluid communication with the fluid flow-path.13. The regulator of claim 12, further comprising a valve seat carriedby the valve body, wherein the spring biases the control member awayfrom the valve seat.
 14. The regulator of claim 12, wherein the controlmember comprises a hollow tubular sleeve.
 15. The regulator of claim 12,wherein the retention plate is disposed inside of the control member.16. The regulator of claim 12, wherein the diaphragm subassemblycomprises upper and lower diaphragm plates sandwiching at least aportion of the diaphragm.